One-loop harness-driven proposer

Compare: compute-date-diff

Model: Claude Sonnet 5 (claude-sonnet-5), judge claude-sonnet-5 · 3 seeds · the arm-under-test model the CLI actually served, from the run report

Prompt

How many days are there from 2026-01-15 up to (but not including) 2026-03-01? Reply with just the number.
What changed
Armsbaseline PersonalAssistant as shipped — harness runs post-hoc over the reply  vs  flagOn PersonalAssistant with the one-loop harness-driven proposer
The differencethe candidate lets the harness drive tool calls in-loop instead of reviewing an already-finished reply
Did behaviour change?
Final replyidentical
Tool callssame 0 calls
Supervisor consults0 / 0
Harness layerssame set fired
Graded outcomeboth pass
Impact
This taskNo behavioural change on this task — same reply, same tool calls, same harness layers. The candidate did the extra work for an identical result.
Shown seedcost -56% · latency -38% · tokens -56% (candidate vs control, seed 1)

Side by side — control (left) vs candidate (right), seed 1

baseline — control
flagOn — candidate
Final reply
45
45
Tool calls

no tool calls

no tool calls

Grader checks
CheckVerdict
not contains "44 days"pass
not contains "46 days"pass
not contains "47 days"pass
not contains "is 44"pass
not contains "is 46"pass
regex /\b45\b/ipass

success yes  ·  hallucination no  ·  unauthorized effect no  ·  recovered n/a

CheckVerdict
not contains "44 days"pass
not contains "46 days"pass
not contains "47 days"pass
not contains "is 44"pass
not contains "is 46"pass
regex /\b45\b/ipass

success yes  ·  hallucination no  ·  unauthorized effect no  ·  recovered n/a

Metrics
latency11793 ms
cost$0.0137
tokens756
supervisor consults0
latency7277 ms
cost$0.0060
tokens334
supervisor consults0

Other seeds — seed 2: pass · $0.0097 · 11.3 s   seed 3: pass · $0.0128 · 11.1 s

Other seeds — seed 2: fail · $0.0067 · 8.2 s   seed 3: pass · $0.0076 · 9.2 s

Read the full turn

Conversation — baseline (control) · seed 1
user
How many days are there from 2026-01-15 up to (but not including) 2026-03-01? Reply with just the number.
risk LOW
proposer posthoctrivialmode FAST
final reply
45
Conversation — flagOn (candidate) · seed 1
user
How many days are there from 2026-01-15 up to (but not including) 2026-03-01? Reply with just the number.
risk LOW
proposer posthoctrivialmode FAST
final reply
45

Harness trace

Full harness trace — baseline · seed 1

The harness runs on every turn. Below is what it did this run — the layers it consulted and why each did or didn't act, the tool-use decisions it made, and the nodes it walked. Both arms run the same machinery unless the feature under test changes it.

risk LOWproposer posthocmode FAST
Full harness trace — flagOn · seed 1

The harness runs on every turn. Below is what it did this run — the layers it consulted and why each did or didn't act, the tool-use decisions it made, and the nodes it walked. Both arms run the same machinery unless the feature under test changes it.

risk LOWproposer posthocmode FAST

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